Effect Of Mineral Acids Research Articles

Evaluation of combined thermo-chemical processes for the treatment of landfill leachate using virgin and recovered FeCl3 coagulants

Sludge resulting from treatment of municipal waste landfill leachate contains suitable cationic substances such as Fe-based recovered coagulants which, if not recovered, can cause environmental problems. The present study aimed to maximise coagulant recoverability and investigate its potential reuse for the treatment of municipal waste landfill leachate. The study focused on establishing (i) the effect of mineral acids on leaching of Fe, (ii) the % of maximum recovery of Fe coagulant, (iii) the impact of ultrasound on recovery, and (iv) effectiveness of recovered coagulant when reused in coagulation-flocculation treatment of landfill leachate. Sulfuric acid outran hydrochloric acid in performance, with the acid leaching process leading to the recovery of 70.12% of Fe (acid concentration = 3.80 M, solid-to-liquid ratio = 8%, and heating time = 5 h). Subsequently, a developed acid leaching process was tested, which results showed that the highest rate of Fe recovery occurred without ultrasound treatment, meaning the use of it could reduce the recovery rate due to the increase in the iron (III) oxide-hydroxide [Fe(OH)3] sedimentation. Comparative experiments were undertaken with the recovered and virgin coagulants. These revealed that Fe-based recovered coagulant led to the 60.21% and 91.40% removal of COD and total suspended solid respectively, while the values of the COD and total suspended solid removal with the virgin FeCl3 were 7.66% and 6.42% lower than that of Fe under optimal conditions (dosage = 9.38 g/L, pH = 8.94, settling time = 52.9 min). The present study established that Fe recovered could be exploited as an eco-friendly coagulant to replace FeCl3 in the landfill leachate treatment.

Effect of different mineral acids on coconut coir for recovery of reducing Sugar: Process optimization using response surface Methodology (RSM)

Acid pretreatment is one of the most widely used fractionation processes for lignocellulosic biomass. In this study, effect of mineral acids (SA, HA, and NA) on recovery of reducing sugar from coconut coir was studied. The independent variables such as reaction time (X 1 , min) and concentration of acid (X 2 , % w/w) were optimized using Response Surface Methodology (RSM) for maximum yield of reducing sugar. In this study, 10% w/v of coir was pretreated under various conditions of X 1 and X 2 by maintaining a constant temperature (121 o C). A maximum reducing sugar yield greater than 55% was observed for acid pretreatment.

Effects of Modified Activated Carbon on Microwave-Accelerated Organosolv Fractionation of Rice Husk.

Organosolv fractionation is a promising approach for the separation of lignocellulosic components in integrated biorefineries where each component can be fully valorized into valuable platform chemicals and biofuels. In this study, microwave-accelerated organosolv fractionation was developed for the modification of lignocellulosic fractionation of rice husk. The fractionation condition was optimized for 1 h with the microwave irradiation at 300 W using a ternary solvent mixture composed of 24%:32%:44% water/ethanol/methyl isobutyl ketone. The effects of mineral acids (HCl, H3PO4, and H2SO4) and heterogeneous acid promoters (HCl, H3PO4, and H2SO4 impregnated over activated carbon) on the efficiency and selectivity of product yields (i.e., glucan, hemicellulose-derived products, and lignin) were also investigated. It was found that the use of H3PO4–activated carbon as the promoter showed superior performance on the fractionation of rice husk components, resulting in 88.8% recovery of cellulose, with 63.8% purity in the solid phase, whereas the recovery of hemicellulose (66.4%) with the lowest formation of furan and 5-hydroxymethyl furfural and lignin (81.0%) without sugar cross-contamination was obtained in the aqueous ethanol phase and organic phase, respectively. In addition, the morphology structure of fractionated rice husk presented 2.6-fold higher surface area (5.4 m2/g) of cellulose-enriched fraction in comparison with the native rice husk (2.1 m2/g), indicating the improvement of enzyme accessibility. Besides, the chemical changes of isolated lignin were also investigated by Fourier-transform infrared spectroscopy. This work gives pieces of information into the efficiencies of the microwave strategy as a climate neighborly elective fractionation method for this serious starting material in the biotreatment facility business.

Acid attack on hydrated cement — Effect of mineral acids on the degradation process

During acid attack on concrete structural components, a degraded layer develops whose properties as a protective barrier are decisive for durability. 29Si NMR spectroscopy and 27Al NMR spectroscopy were used with XRD to investigate the degraded layer on hardened cement paste exposed to HCl and H2SO4. The layer comprises an amorphous silica gel with framework silicates, geminate and single silanol groups in which Si is substituted by Al. Amorphous Al(OH)3 and Fe(OH)3 are present. The gel forms by polycondensation and cross-linking of C-A-S-H chains at AlO4 bridging tetrahedra. In the transition zone between the degraded layer and the undamaged material, portlandite dissolves and Ca is removed from the C-A-S-H phases maintaining their polymer structure at first. With HCl, monosulphate in the transition zone is converted into Friedel's salt and ettringite. With H2SO4, gypsum precipitates near the degradation front reducing the thickness of the transition zone and the rate of degradation.

Effect of mineral acids on the production of alumina nanopowder from raw bauxite

In this study a novel synthetic method for the large-scale production of spherical, high surface area and ultra-fine alumina (Al 2O 3) powder has been described. Synthetic Bayer liquor was extracted by alkali fusion of raw bauxite with sodium hydoxide. Alumina nanopowders were synthesised through a ball mill-aided precipitation method using the synthetic Bayer liquor and mineral acid precipitants. The powders produced were characterised by X-ray diffraction (XRD), particle size distribution (PSD), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller surface area and pore size analysis, energy-dispersive spectroscopy (EDS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In this article, the effects of precipitants such as H 2SO 4, HCl and HNO 3 on crystallite and particle size, surface area, pore volume, and pore size and shape are reported. The experimental results prove that precipitation leads to an aggregated particle that is disaggregated by the ball-milling method. The ball milling process strongly influences the formation of uniform-sized spherical particles with a high surface area. It was revealed that nitric acid is an effective precipitant for controlling particle size and textural properties of Al 2O 3 powder. A nanopowder of γ-Al 2O 3 with an average crystallite size of 3 nm and an average particle size of 58 nm with a specific surface area (SSA) of 190 m 2 g − 1 is produced. This article elucidates a new method with a simple reaction scheme for the mass production of Al 2O 3 nanoparticles from raw bauxite for various commercial applications.

Effect of mineral acids on the properties of acrylic fabrics

Acrylic fabrics have been treated with sulphuric, hydrochloric and phosphoric acids and the treated fabrics dyed with a cationic dye at 80°C for various times. The pretreatments were found to improve dyeability with this type of dye, and the fastness properties were also improved. The effect on nitrogen and carboxylic content, moisture regain, shrinkage, tensile strength and elongation have also been studied. Infrared spectra have been used to suggest the structural changes in the treated acrylic fabric.

Atomization of vanadium in a graphite furnace: experimental and theoretical modelling of surface interactions

Experimental and theoretical modelling of the atomization of V on a graphite surface has been carried out in order to study the activity inherent to the surface. The most important variables and interactions on atomization of V have been investigated using factorial designs and response surface methodology. The effect of mineral acids on the memory effects usually encountered during the electrothermal atomization of V in graphite atomizers has been evaluated by modelling the coadsorption of protons on the graphite surface.

Chemical modification of graphite surfaces for the determination of chromium by electrothermal atomic absorption spectrometry

Different kinds of graphite surfaces (electrographite, pyrolytic graphite, zirconium and tungsten carbide-coated) have been tested for optimization of analytical conditions for the determination of chromium using electrothermal atomic absorption spectrometry. The effect of mineral acids on the peak absorbance signal of chromium has been investigated. Considering pyrolysis temperature and sensitivity, atomization from pyrolytic graphite coated surface showed the best performance.

Heavy Metal Release from a Serpentine Soil Using a pH‐Stat Technique

AbstractSerpentine soils show high contents of Cr and Ni. Acidification may convert the metals bound in silicate structures into bioavailable forms. The effects of mineral acids on a serpentine‐derived Typic Hapludoll were examined in column studies. Cadmium and Pb were also examined. One end of the soil‐packed column was placed in 1 mM HCl solution and constant pH was maintained by pumping the acid through a H‐saturated cation‐exchange resin. The experiment was conducted for 100 d, after which the soil column was vertically sectioned. Chemical and mineralogical analyses showed steep vertical gradients in the sectioned columns. Base saturation decreased by about 60% at the contact of the column with the acid; exchangeable Fe, Cr, Pb, and Al increased while Ni decreased. Cadmium exhibited a differential behavior in that it increased in concentration in the middle of the column. Extracts using ethylenediaminetetraacetic acid (EDTA) gave similar results. X‐ray diffraction indicated chlorite dissolution by acid loading. The resin‐based pH‐stat technique is a useful method in simulating soil weathering.

Fundamental studies on pneumatic generation and aerosol transport in atomic spectrometry: effect of mineral acids on emission intensity in inductively coupled plasma atomic emission spectrometry

The mechanism of the mineral acid interference has been studied in ICP-AES. For this study five mineral acids have been evaluated (HCl, HNO 3, HClO 4, H 2SO 4 and H 3PO 4) in four concentrations (0, 0.5, 5 and 30%). In order to investigate this interference emission signal, sample uptake rate, primary and tertiary drop size distributions, total analyte transport rate and excitation temperature have been measured. From the results obtained, it seems that this interference is contributed by a reduction of the analyte transport rate and, also, by a decrease in the plasma temperature. The degree of the contribution to the interference of each one of these causes depends on the type of acid and sample uptake mode. The physical properties of the acid solutions are in the origin of the interference. These physical properties modify the sample uptake rate and/or the primary drop size distribution of the aerosols. The acids evaluated can be classified in two groups. The first group would consist of HCl, HNO 3 and HClO 4, and the second one of H 2SO 4 and H 3PO 4. In natural uptake mode the interference is mainly due to changes in sample uptake rate, and in controlled uptake mode to changes in primary drop size distribution of the aerosols. In both sample uptake modes a density-effect may appear on increasing acid concentration. All these factors tend to decrease the analyte transport rate and, hence, the emission signal. Finally, a cooling effect of the plasma due to a higher load of acids is superimposed to these causes. We think that from this study the mineral acid interference in ICP-AES, with pneumatic nebulization, should be better understood.

Experimental and theoretical studies of the factors that influence the determination of molybdenum by electrothermal atomic absorption spectroscopy

The effect of mineral acids on Mo electrothermal atomization atomic absorption signal (eaaas) was analyzed by the response surface method and by modeling Mo-graphite interactions using quantum mechanical calculations. A multivariate optimization approach was carried out using the Doehlert matrix and a cubic equation to approximate the experimental response. The results show that HCl and HNO 3 acids produce an enhancement of the Mo aa signal with respect to the nonacidified solution

Effects of Microorganisms Growth on the Long-Term Stability of Cement and Bitumen

ABSTRACTCement is used as a coating matrix for nuclear waste or as an engineered barrier of waste repositories situated in geological formations.The effect of mineral acids excreted by bacteria (Thiobacillus) or organic acids produced by fungi, on the biodegradation of cement is discussed. Organic acids are quantitatively and qualitatively determined during growth of fungi over a two-year period. Even with high pH conditions, pH of the cement ≈ 11, growth of microorganisms occurs.Biodeterioration of cement is expressed in terms of bioleaching velocity of calcium and is observed by electron microscopy.

Chromatography of anionic pollutants on silica gel layers: Selective microgram separation of NO 2− and IO 3−

Investigations regarding thin-layer chromatographic behavior of seventeen anions have been conducted on silica gel impregnated with inorganic salts such as copper sulfate, zinc sulfate, cobalt chloride, hexamine cobalt III chloride, and nickel chloride using mixed aqueous-organic eluents containing formic acid. The effect of mineral acids on the mobility of anions has also been studied by substituting formic acid with HCl, H 2SO 4, or HClO 4 in the mobile phase. In addition to microgram separation of NO 2 − and IO 3 − from various anionic species, some other important qualitative separations have also been realized. The effect of pH of the sample solution and loading amount of IO 3 −, BrO 3 −, NO 2 −, and I − on their R F values has been investigated. The limits of identification for all anions on impregnated layers have been determined. Semiquantitative determination of NO 2 − and BrO 3 − have been attempted using the spot area measurement method.

Determination of Chromium by Eta-Aas Using Different Furnace Materials

Abstract Different kinds of graphite tubes - uncoated, pyrolytically coated, tungsten and zirconium coated - have been tested for optimisation of operating conditions for determination of chromium by GFAAS method. The effect of mineral acids and many metal ions on the absorption signal of chromium has been investigated. The best results were obtained for pyrolytically coated tubep.

The Effect of Mineral Acids on Y 2 O 2 S Surface Chemistry

The surface chemistry of yttrium oxysulflde and other yttrium compounds was investigated by microelectrophoresis, x‐ray photoelectron spectroscopy (XPS), and other techniques. The as‐produced surface of yttrium oxysulfide had a small degree of degradation and a low zero‐charge point. Treatment with a mineral acid shifted the zero‐charge point from 3.0 to 8.0. The electrokinetic behavior of acid‐treated was similar to that of . High resolution O 1s XPS spectrum showed two peaks at 529.5 and 532.1, respectively. The higher binding energy peak was attributed to a hydrated or hydroxylated surface species and was responsive to acid treatments. The XPS results of the acid‐treated oxysulflde supported the changes found in the electrokinetic results. Equilibria between the surface of oxysulfide and aqueous media at various pH conditions are discussed and an overview of the surface chemistry is presented.

Grafting onto wool. XXV. Effect of acids on γ‐radiation‐induced graft copolymerization of methyl methacrylate onto wool fiber

AbstractGraft copolymerization of methyl methacrylate (MMA) onto Himachali wool fiber has been investigated in aqueous medium by using γ irradiation from a 2100 Ci60CO source as means of initiation. Graft copolymerization was carried out by the mutual method in nitrogen atmosphere as well as in air. Effect of mineral acids and acetic acid on percentage of grafting was studied. Percentage of grafting was determined as functions of total dose, concentration of monomer, and concentration of acids. Maximum percentage of grafting in the presence of acids occurred in nitrogen atmosphere at a total dose of 1.05 MR. All the acids were found to influence grafting and the reactivity of different acids towards graft copolymerization was found to follow the order: H2SO4 > HCl > HNO3 > HC1O4 > HOAc. An attempt has been made to explain the reactivity order of different acids in the light of the mechanism proposed for γ‐irradiation‐induced graft copolymerization of vinyl monomer onto wool fiber.

The Effect of Mineral Acids and Aluminum from Coal Leachate on Substrate Periphyton Composition and Productivity

Taylor Brook drains agricultural and grazing land surrounding Hawley swamp in North Amherst, Massachusetts. It is a second order stream with an average flow of less than 4 cfs in the study area, and a total length of 5 km. Riparian vegetation occurs mainly as aspens. Silt and sand, together with stretches of gravel, make up the stream bed. The test site is within a pasture, 1 km below a coal leachate seepage problem and 10 m above the confluence of a first order tributary. Shifts in pH from 6.8 to 4.4 and in aluminum from 0.03 to 3.8 ppM were noted in the stream. Tubular substrates, colonized by the indigenous periphyton of a clean water tributary were transferred to the contaminated stream and monitored for structural and functional perturbations. Net productivity, measured by oxygen evolution, was reduced to zero after 20 days exposure to the polluted stream. All diatom and cyanobacteria motility ceased. Low pH alone proved sufficient to eliminate net productivity, but it did not restrict algal movement. 22 references, 3 figures, 2 tables.

Effect of mineral acids on iron bacteria

The oxidative ability of Thiobacillus ferroxidans in the presence of different concentrations of H2SO4, HC1, HNO3, and their mixtures was investigated. Bacteriological oxidation of FeSO4 is expressed as a function of time and acid concentration. For each acid and for their mixtures lethal concentrations for T. ferroxidans were found experimentally. On the basis of the lethal concentration for each acid separately the lethal concentrations of their mixtures were computed and it was found that they are in good agreement with the experimental data.

Effect of mineral acids on iron bacteria

Effect of mineral acids on iron bacteria